


imposter

by Ninji



Category: Undertale (Video Game)
Genre: Among Us crossover, Angry Sex, Angst, F/M, Grief/Mourning, M/M, Off-screen death, Other, Rough Sex, a-and on-screen death, reader has both a penis and vulva, reader is unnamed character, so much angst my dude
Language: English
Status: Completed
Published: 2020-11-26
Updated: 2020-11-26
Packaged: 2021-03-09 21:27:21
Rating: Explicit
Warnings: Graphic Depictions Of Violence, Major Character Death
Chapters: 1
Words: 3,203
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27722786
Author URL: https://archiveofourown.org/users/Ninji/pseuds/Ninji
Summary: creative title for an Among Us AU, eh?
Relationships: Red/Reader, Sans (Undertale)/Reader
Comments: 1
Kudos: 15
Collections: It's Snowing Somewhere Else: An Undertale Themed Secret Santa 2020!





	imposter

**Author's Note:**

  * For [Vivalavidapasta](https://archiveofourown.org/users/Vivalavidapasta/gifts).



> hello all!!! keep in mind i only played this game like uhhhhhh twice ever (i did my research though so it’s okay!)

The expanse of space was a much different experience than how it’s portrayed in movies. The space in movies is never genuine, always so fake and hollow. But being able to experience a truly limitless stretch of millions, billions, an _infinite_ amount of stars, it’s all so…

...It’s not what Red wanted it to be. 

He wants to go home. 

He wants Boss back. 

He should have never signed up for this program. He expected fun with friends, a learning experience, maybe to grow even closer to the participants. Something he _craved_ , since he already wasn’t the best at making friends. 

But instead, it seems everyone is growing apart. 

A sudden fury washes over him; he bangs his fist against the thick glass and lets out an agonized growl. He can’t _take_ it anymore. He doesn’t know exactly who the imposter is but he just wants to know _why_ . _Why_ would someone do this to them? _Why_ would they find joy in taking the life of those who just wanted to go to space? _Why did they have to take his brother from him?_

The sensation of hands resting on his shoulders makes Red jump. He doesn’t even realize he’s been crying until he looks up and his vision is unfocused. 

He wipes his eyes with the glove of his suit and looks behind him. It’s the human. 

“Hey,” they say to him. Their helmet is off, so the concern in their eyes is as plain as day. “C’mon. We gotta finish up these tasks. Can you help me?”

Red doesn’t say anything for a good moment and a half, but eventually he looks to the ground and mutters a disinterested “i don’t wanna.”

“Please? You have to take your mind off —“

“distractin’ me ain’t gonna bring paps back,” he snarls. 

The human isn’t sure how to respond. They rub his back with comforting circles. “We should at least stick together. I don’t want anything happening to you, man.”

“that makes one of us.”

The absolute resignation in his tone makes them want to wince. Luckily they’re able to hide it, so as to not make him feel worse. “C’mon, don’t — don’t say that. Please. Just… come with me? For me. I’m scared. I don’t wanna be alone.”

Red heaves one long sigh. He looks at the human again, seemingly studying them. Eventually, he swallows and nods. “yeah. a’ight, yeah, i’ll come with you.” 

They smile at him, thankful for his decision. They hold his hand while he bends down to pick up his helmet. “Let’s go to electrical. I have to fix the wiring in there and I-I’d feel better if you keep lookout.”

The whimper in their voice, though barely noticeable, makes his Soul clench. “yeah,” he says again, making for Electrical with their wrist in hand. 

  
  
  


“Hey, Papyrus,” The human greets when they arrive. Papyrus seems jovial and just plain happy to see them… then his eyes meet Red and he visibly stiffens.

“Oh, hello human! And Red. I trust you’re getting your duties done?”

“Yup! I’m just getting ready to fix the wiring in here. Red’s just keeping me company.”

Both the human and Papyrus look to Red to see if he has anything to add on. He doesn’t — instead he just stands there, wrist still being held by the human, the air of despondence practically wafting from him. 

Papyrus looks uncomfortable. “R-right. Well. So long as you finish your tasks as well, Red.”

There is no response. 

Poor Papyrus looks like he is itching to leave. “I just finished calibrating the distributor, so I’m pleased to say I’m making good progress! I will see you around, little human!”

They wave as the skeleton hurries past them, off to complete the next task on his list. “Bye Paps! Be safe!”

_Be safe._ Ugh. Red’s spine tingles with a special sort of disgust when he hears that phrase. No one should _have_ to tell someone to be safe. Not on this ship. But now, now that it’s become apparent that there’s someone on this ship willing to kill their crewmates, it’s become a common phrase. 

If Boss was still here, they wouldn’t have to be saying that stupid fucking phrase. 

By the time his attention is back on the human, they’re busy fondling the wires and trying to solder them back together. The concentration in their eyes is razor sharp, all their focus on their task. Red can see why they asked him to keep watch. They’re so tiny; it would be so easy to take them out like this. Very little struggle, considering everyone else is bigger than them. 

He couldn’t lose someone else…

He approaches them, hands upon the wall and boxing them in from behind. “‘ey,” he says softly so as to not frighten them. 

They don’t look up but they hum inquisitively. 

One of Red’s hands moves from the wall to rest on their waist. “i missed ya,” he whispers with just a hint of genuine sorrow. The hand trails up their side, the fingers lingering where the side of their breast, underneath that thick and cumbersome suit. “wanna fool around?”

“I’m working,” The human replies. Despite her words their head leans back and rests on his sternum. “I really needa do this first…”

“c’mon, just a quickie. ya still got time to finish later.” His voice drops to a sinful whisper, one that can only be described as candy to their ears. It’s such a weakness for them and he’ll be damned if he never uses it against them. “just a quickie… it’ll feel so good.”

“Red...”

“please? i needa let off some steam.”

They knew _exactly_ what he meant by that phrase… considering all that has happened in the past few days, it would be pretty difficult to _not_ know what he was referring to. And Red doesn’t say please often, especially not in a serious context. The human sighs and closes the electrical panel.

“Let’s go to my room, okay? So it’s just us two.”

Red lets out a low hum, clearly satisfied. “mmh, there ya go.”

They grab his hand and lead him to the sleeping quarters, locking the door behind them so their alone time won’t be disturbed. Red grabs them and pulls them close before they even have a chance to take the suit off. 

“i don’t think i can hold back. i _needa_ be rough, and i’m warning ya now, got it?”

“I know,” the human says gently. “I understand. Be as rough as you need.”

His shark-like grin splits his face when he nudges them away. “take it off. alla’ it.”

They obey without hesitation, and though it takes them both a good five or ten minutes to take off the troublesome suits, eventually they’re both standing there, bones and skin all on display, naked as the day they were born. 

Red pounces, pushing them down onto one of the cots with a feral growl and obnoxious squeak of old metal. The sudden force nearly knocks the air out of their lungs, and it’s hard to get their breath back with a skeleton’s tongue shoved down their throat. 

They whimper when Red’s strong grip holds their chin in place, their puny human tongue no match for that slimy, monsterous appendage. 

“heh,” Red pulls away, “i can smell how horny y’are. nasty lil’ fuck.”

“Yeah,” they moan, finally able to draw some air into their lungs. “Only for you _uuuuu, fuck_ …”

Red’s hand has fallen to their half-hard dick, trailing his dangerously sharp claws up the underside. “like that?” he snarks, giving it a squeeze and relishing their squirms. _“answer me.”_

_“Yes.”_

“yeah ya fuckin’ do. lay back.”

The command leaves little room for objection, so they do what he says and scoot onto their back, spreading their legs akimbo. Red doesn’t waste any time ducking down and tonguing at their slit, all the while giving their dick harsh strokes. The tight grip hurt, but it only made them crave _more._

“Red, _fuck—”_

A growl rumbles in the skeleton’s ribcage, no doubt excited by the human’s little squeaks and moans of bliss. His mouth hangs open, glowing tongue slithering as deep as it could into their cunt, slurping crudely at it like a starving man. 

Their orgasm approaches like an oncoming tidal wave; toes curling, hips moving on their own accord, little squeaks escaping their lips while they clench the pitifully thin sheets behind their head. 

“heh, i know that face,” Red chuckles, his voice surprisingly coherent despite his tongue digging for gold in their crotch. His fingers roughly caress the head of their dick, gathering the precum that had begun to pool and smearing it all over so it serves as lube while he jacks them off. The pace his hand sets is impossibly fast, and the human finds their cum landing on the top of his skull before they can even register the fact that they climaxed. 

“didn’t even get a chance to tell ya to cum fer me.” Red eyes them sultrily, making a show of using his hand to wipe the cum off the crown of his skull and onto his tongue. “‘s been a while, hasn’t it?”

They pant harshly, face flushed. “I… yeah. It has, I guess.”

“ya wanna ride me or do ya wanna get pounded into the bed?”

Oh, if they fuck on this creaky little cot, it’s certain that the whole ship will hear their coupling. But now, their mind foggy with post-orgasm bliss, it’s a little hard to care. “Doesn’t matter, just — just _fuck_ me, _please.”_

“i ain’t gonna hold back. not today. just lettin’ ya know —“

“It doesn't matte—“

Red pounces on them, razor teeth alarmingly close to their jugular. “don’t _fuckin’_ interrupt me.” His maw opens, almost like he is preparing to rip open their throat, but only the very tips of his teeth dig into the skin; it’s a threat, one that reads loudly and clearly. He shifts to jack himself off for a moment, only moving his mouth away from them to line himself up to their sopping cunt. “ya ready?”

“y-yeah, i — _!!!”_ Their words morph into a guttural sound, some weird mix between a grunt and a scream, when Red hilts himself without any further warning. Even after the thorough toungefucking, nothing could prepare them for the sheer _girth_ of his cock. Their hips stiffened and they instinctively tried to move away, but the skeleton gripped onto their upper arms before they could. 

“good, ‘cuz i _don’t care._ ”

The way he fucks into them could only be described as _angry_. It was obvious that he was pissed, that he was distressed, and this was just his way of letting off steam. He uses them like they’re nothing more than a fleshlight, a toy for his own pleasure. 

“R-Red, guh, _fuck—“_ Their voice is reduced to a choked up garble of sounds, biting down on their finger to muffle any obscene sounds to no avail. Their other hand flies to their neglected dick, leaking out a _copious_ amount of pre. Just a hard squeeze and a little stroking around the head and they already find themself close again. 

Then the human’s hand is slapped away. “nah-uh,” Red grunts. “ya don’t get ta’ cum til i say so. that’s _my_ dick, not yers. _got it?”_ He grips tightly around the base and merely laughs at the human’s weak attempts to struggle under him. “answer me, _slut._ who’s dick is this?”

Another squeeze has them crying out desperately, _“yours!”_

“and what about this cunt, huh? who’s this wet little pussy belong to?” He thrusts harder and deeper inside them for emphasis. 

“It’s _yours!_ Your pussy, Red, yours, _fu-u-uck!”_

Red’s grin is a weird blend of sardonic and hungry, thin drool seeping past his gnashed teeth and falling onto their belly. “yeah, good fuckin’ human — _mmph_ , let me hear ya. i don’t give a _shit_ if the otha’s complain, all that matters is…” he trails off into a slurry of grunts and groans, obviously close to blowing his first load of the night (night? day? it doesn’t feel like time is even real while in space). He releases his deathgrip on the human’s dick and gives it long strokes, rubbing his thumb bone around the head and especially around their little slit; Red’s hand is coated with cum in no time at all while they squirm on the cot, biting one of their hands to contain their raptured screams. Red can’t help but think that they make _such_ a pretty sight, the best sort of distraction he could ask for tonight. Maybe he can’t drown himself in beer in space, but for now, this is just as good. 

“R-Red,” they mumble out, voice shaking with each unrelenting thrust into their tight heat. “too much, so _much…”_

“yer fine,” the skeleton breathes out, husky and equally as shaky. “just sit there and take it like a nice lil slut, eh?”

They throw their head back onto the paper-thin pillow and whine out miserably, the overstimulation almost becoming too much for them. Thankfully, Red cums into their cunt with an aborted shout tapering off into a growl. He leans forward and buries his head into the crook of their neck but to their surprise, he doesn’t bite them. He’s bitten them every other time they’ve fucked, they realize, except for now. 

By the time Red finishes emptying himself into them, the crimson fluids have leaked onto the sheets of the cot and left a sizable stain. If the smell of sex doesn’t give it away, anyone who walks in will surely be able to figure out what just took place. 

The human breaks the post-coital silence. “Why didn’t you bite me?”

Red doesn’t answer right away. He pulls back so he’s sitting on his knees, erection having already dissipated leaving nothing but a bare pelvis. “i uh,” he glances at the wall to the side, “if i did i pro’lly wouldn’t be able t’hold back. not tonight, y’know?”

They nod with solemn understanding. 

“so, heh, ready for round two? it’ll take a sec fer me to get it up again but —“

“Hey Red?”

He finally turns his head to them, red pinprick pupils landing on their face. “yeah?”

“I know things have been hard lately but… do you miss your brother?”

It takes him a moment to process the question, but once he does his features twist into disgusted, disbelieving scowl. “the fuck ya mean do i miss him?”

“No, no, I mean like… hold on.” They ponder for a moment, moving their hand in a way like it will turn the gears in their head faster. “If… if there was a way to be able to see him again, would you do it?”

That obviously isn’t any better than the first question, if the shaking of Red’s head means anything. “too soon, man. fuck, ya can get yerself off, i ain’t havin’ this conver—“

_“Wait.”_

Their hand grips his forearm with an impossibly tight grip right when he makes the move to leave. He looks down at their hand, then at their face — they’re smiling, manic and… unnatural. 

“the fuck’s yer problem?” Red nearly yells at them, trying to pull his arm free with no avail. “let go, i said i’m done!”

“But why? Don’t you wanna see your brother? You don’t have to be alone. You’ve been so sad since he disappeared, why pass up on an opportunity like this?”

“yer fuckin’ crazy!”

“Don’t you love your brother, Sans?”

He swallows, staring at her with a wide-eyed look like deer in headlights. Then it’s gone, cold and scornful disgust jumping in to take its place. 

“don’t call me that.”

He moves to leave the room, to get away from whatever nonsense decided to spill from their mouth and remind him that _his brother is gone_ , _he doesn’t need to be reminded that his brother is gone, he agreed to this so he could get away from it all_ , then suddenly, there’s a shift in the atmosphere; small, barely noticeable, but something oh, so very wrong. 

He doesn’t even get a chance to turn around. 

The pain doesn’t register, not at first. In fact, the… _appendage_ is what he notices first. It’s hard _not_ to notice a tentacle jutting out of your chest. Out of your sternum. Right through your _Soul._

Red can’t speak. He tries, but the mana in his body is unable to make any sound. In fact, the pain caused by attempting to speak is what he feels first. Then, it hits him all at once like a sixteen-wheeler. 

The tentacle retracts as quickly as it appeared, leaving behind a gaping wound in his Soul so large that it actually had to stretch around the damn thing. He finds himself unable to breath in, rendering his mana circulatory system useless. In a painful move, he whips his head around in time to see a gaping maw taking up almost the entirety of the human(??)’s face. It’s not a normal human mouth, but he doesn’t get a good chance to look at it for long, other than noting the viscous drool and jagged teeth; once the tentacle retracts completely, the fleshy, drooly orifice disappears without a trace, leaving only their cheerful, smiling face and bright eyes. He gasps and falls forward, trying to catch himself with his hand but the moment it makes contact with the ground it vanishes in a puff of dust. 

“See, Red?” They say, much too happy considering. It was sickening. “I know you’re scared, but it's okay! You get to see your brother, and I get to feed on your Soul. It’s a win-win!”

He wants to curse at them. He wants to scream. He wants to lunge at them and tear them open, but he’s too incapacitated to do anything. The light of his Soul is sputtering pathetically, and his limbs already feel numb — a sure sign that the dusting was advancing quickly. 

He never thought dying would hurt this bad. Another surge of rage makes him tremble, the thought that Boss, that his Papyrus had to go through this same agony makes him feel nauseous, moreso than the pain itself. He didn’t protect him like he was supposed to. 

He could’ve been a better brother. But in a sense, the human ( _no_ , he mentally kicks himself _, they’re something even worse. something unknown. an imposter.)_ is right: if he gets to see his brother again, maybe he’ll get a chance to redeem himself. 

He hopes they’ll meet in the afterlife. 

The Imposter pats his head condescendingly, chalky dust clinging to the palm of their hand. They say something, sounding pretty giddy, but he can’t discern their words. His mind is too far gone. 

He falls forward, disappearing into a cloud. 

The Imposter puts their suit back on, stepping over the pile as if it was just a regular mess and not the remains of a living being (let alone someone they just finished fucking). Their hunger still wasn’t satisfied, resulting in an aching feeling radiating from deep within their gut. Maybe if they were lucky, Papyrus would still be nearby...


End file.
